* add print transformer & unify print format, test=develop

* remove using of dygraph_to_static_func, test=develop

* remove python stdout capture, test=develop

* fix compatibility problems for PY2, test=develop

* fix detail error, test=develop

* fix type analysis bug, test=develop

* fix print tuple compatible error in PY2, test=develop

* replace get_func to declarative, test=develop

* fix detail bug, test=develop

* fix some detail problems, test=develop

* change visit_call in print transformer, test=develop

* add trace op, test=develop

* Optimized the implementation of trace op, test=develop

* fix a bug of include in trace_op.h, test=develop

* move trace API from creation to math, test=develop

* modified en doc. test=develop

* add complex trace api

* add complex sum api, test=develop

* modified en doc of complex sum and trace, test=develop

* modified doc and trace API, test=develop

* modified en doc of trace and sum, test=develop

* modified comment in complex kron API, test=develop

* OP Should Not Have Unused Input, test=develop

* add GetExpectedKernelType, test=develop

* add batch fc op, test=develop

* add batch_fc_op, test=develop

* fix untest, test=develop

* rm check_dygraph, test=develop

* fix comment, test=develop

* fix comment, test=develop

* define fluid alias in paddle.tensor and paddle.nn dir test=develop

* from layer import loss in paddle.nn dir test=develop

* add to_readable_code method, test=develop

* polish doc details, test=develop

* polish doc note, test=develop

* fix unittest error, test=develop

* fix coverage, test=develop

* add print test, test=develop

* add print param, test=develop

* hidden to_readable_code api, test=develop

* remove original tool methods, test=develop

* remove old api using code, test=develop

python API(get_tensor_from_selected_rows and tensor_array_to_tensor)error message enhance, test=develop (#23636)

* adapt old version pretrain model load, test=develop

* fix infer error & multiple input error, test=develop

* update index sample

* add decorator, test=develop

* add fake_interface_only, test=develop

* remove some dygraph_not_support, test=develop

* change dygraph to imperative, test=develop

* add kron op and its python API, doc and unittests.
* add kron in paddle.complex

fix the bug in inferVartype in the uniform_random op, add the support the set of dtype 

* API/OP (affine_channel, group_norm, layer_norm, random_crop, unpool, log_loss) error message enhancement test=develop

* Add cholesky_op forward part. test=develop

* Complete cholesky_op forward part. test=develop

* Add cholesky_op backward part. test=develop

* Complete cholesky_op backward part. test=develop

* Refine cholesky_op error check and docs. test=develop

* Add grad_check unit test for cholesky_op. test=develop

* Fix sample code in cholesky doc. test=develop

* Refine some error messages of cholesky_op. test=develop

* Refine some error messages of cholesky_op. test=develop

* Remove unused input in cholesky_grad. test=develop

* Remove unused input in cholesky_grad. test=develop

* Fix stream for cusolverDnSetStream. test=develop

* Update PADDLE_ENFORCE_CUDA_SUCCESS from cholesky_op to adapt to latest code.
test=develop

* Add CUSOLVER ERROR in enforce.h
test=develop

* Fix the missing return value in cholesky. test=develop

* [Dy2Stat] Add test for ptb model. test=develop

* Simplify code for gast.If in is_control_flow_to_transform. test=develop

* Move IsControlFlowVisitor to file utils. test=develop

* Don't use convert_call for build-in func in CallTransformer. test=develop

* Optimize api is_control_flow_to_transform. test=develop

* Polish the document of IsControlFlowVisitor. test=develop

* Use declarative instead of dygraph_to_static_func. test=develop

* Add trainable_statistics in attr for batch_norm
* Unifying behavior of dynamic graph and static graph

* Simplify code for gast.If in is_control_flow_to_transform.
* Move IsControlFlowVisitor to file utils. 
* Don't use convert_call for build-in func in CallTransformer. 
* Optimize api is_control_flow_to_transform. 
* Polish the document of IsControlFlowVisitor.

* Update creation.py

* change int to floor, test=develop

* fix unittest, test=develop

* Indent MSELoss example docs

* Point out input tensors should be of same shape

test=develop

* Document `MSELoss` input and return parameters

test=develop,test=document_fix

* QAT: support range-based quantization and scales from attribute

* added support for channelwise

* Init complex number neural network, test=develop

* Improve doc writing, test=develop

* Fix elementwise add & sub, test=develop

* Fix elementwise mul act, test=develop

* a) add ut for complex variable; b) remove arg act in elementwise_ops. test=develop

Repair unittest: test_dyn_rnn

* add gather split squeeze stack unsqueeze api test=develop

* add gather split squeeze stack unsqueeze api test=develop

* fix bug test=develop

* fix bug test=develop

* fix bug test=develop

* fix bug test=develop

* fix bug test=develop

* test=develop